Honestly, I'm gonna be super lazy and just quote the front page of the site:
> Anyone or anything that accesses data in a Solid Pod uses a unique ID, authenticated by a decentralized extension of OpenID Connect. Solid's access control system uses these IDs to determine whether a person or application has access to a resource in a Pod.
Of course, as a data owner, you could accidentally grant a bad actor access to your data, but presumably you can also revoke that access as well.
> Anyone or anything that accesses data in a Solid Pod uses a unique ID, authenticated by a decentralized extension of OpenID Connect. Solid's access control system uses these IDs to determine whether a person or application has access to a resource in a Pod.
Of course, as a data owner, you could accidentally grant a bad actor access to your data, but presumably you can also revoke that access as well.